Installing Crebs is no pain. It has its PPA at launchpad for Ubuntu.
To install Crebs, open Terminal and type
sudo add-apt-repository ppa:crebs/ppa
sudo apt-get update && sudo apt-get install crebs
Now it should appear in your Menu under "Preferences"(Yes, i use Mint).
Now you can add as many wallpapers you want and set the display time and transition time. You can also change interval between individual wallpapers.
After you finish, just name it and save. A notification will appear telling you that it has been set as Wallpaper.
If you want to further customize the XMl file, you can find it in .crebs directory in your Home Folder.
Crebs still lacks many things, but is certainly a handy and convenient app. Enjoy the slideshow!